Architectural Drawing Conventions, Linework and Lettering
Architectural drawing conventions are the grammar of the sheet. This domain tests whether you can choose a line weight, a hatch and a letter height that tell the reader immediately what is cut, what is seen and what is merely noted. Examiners reward consistency across the whole sheet far more than isolated neatness, and marks are lost fastest where the graphic code contradicts itself.
The line hierarchy (EN ISO 128)
- Continuous thick (0.5–0.7 mm): everything the section plane cuts - wall poché, slabs, columns, the ground line.
- Continuous thin (0.25–0.35 mm): edges visible beyond the cut, dimension and extension lines, leaders, hatching, door leaves, stair nosings, furniture.
- Dashed thin: hidden edges only - a lintel above the cut, a footing below. Use them sparingly; a plan crowded with dashes reads badly.
- Dash-dot thin: centre lines, structural grid axes, symmetry lines, and the cutting plane of a section.
- Keep a thick-to-thin ratio near 2:1 and never use more than three weights on one sheet.
Lettering (EN ISO 3098, type B)
- Single-stroke sans-serif capitals, upright or slanted 15° to the right - never mixed on one sheet.
- Heights: 7 mm for the drawing title, 5 mm for room names and sub-heads, 3.5 mm for notes, 2.5 mm only where space forces it.
- Greek capitals for room names - ΚΑΘΙΣΤΙΚΟ, ΚΡΕΒΑΤΟΚΑΜΑΡΑ, ΚΟΥΖΙΝΑ, ΛΟΥΤΡΟ - plus the area in m². An unlabelled room is an unread room.
Worked example
You are drawing a ground-floor plan at 1:50 and must fix the weight of four items. (a) The external wall at the section plane, taken 1.20 m above floor level: cut, so continuous thick with 45° poché. (b) The kitchen worktop, below the cut and visible: continuous thin. (c) The lintel over the window, above the cut and therefore hidden: dashed thin - but lintels are normally given in the window schedule, so it is omitted to keep the plan to three weights. (d) The structural grid: dash-dot thin, extended past the wall to a bubble. The reasoning is always the same question - is this element cut, seen, or hidden?
Traps
- Door swing drawn dashed; it is continuous thin, drawn as the leaf plus a quarter-circle arc.
- Dimension lines drawn thick, so they compete visually with the walls.
- Walls left unhatched, or hatched at an angle other than 45° with unequal spacing.
- Lower-case or decorative lettering where the standard asks for capitals.
- A legend (υπόμνημα) listing symbols that never appear on the drawing.